[Python-checkins] CVS: python/dist/src/Doc/lib libstdtypes.tex,1.56,1.57

2001年5月02日 13:18:05 -0700

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory usw-pr-cvs1:/tmp/cvs-serv29777
Modified Files:
	libstdtypes.tex 
Log Message:
Added section describing the iterator protocol.
Index: libstdtypes.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libstdtypes.tex,v
retrieving revision 1.56
retrieving revision 1.57
diff -C2 -r1.56 -r1.57
*** libstdtypes.tex	2001年04月23日 13:22:59	1.56
--- libstdtypes.tex	2001年05月02日 20:18:03	1.57
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*** 314,317 ****
--- 314,368 ----
 
 
+ \subsection{Iterator Types \label{typeiter}}
+ 
+ \versionadded{2.1}
+ \index{iterator protocol}
+ \index{protocol!iterator}
+ \index{sequence!iteration}
+ \index{container!iteration over}
+ 
+ Python supports a concept of iteration over containers. This is
+ implemented using two distinct methods; these are used to allow
+ user-defined classes to support iteration. Sequences, described below
+ in more detail, always support the iteration methods.
+ 
+ One method needs to be defined for container objects to provide
+ iteration support:
+ 
+ \begin{methoddesc}[container]{__iter__}{}
+ Return an interator object. The object is required to support the
+ iterator protocol described below. If a container supports
+ different types of iteration, additional methods can be provided to
+ specifically request iterators for those iteration types. (An
+ example of an object supporting multiple forms of iteration would be
+ a tree structure which supports both breadth-first and depth-first
+ traversal.) This method corresponds to the \member{tp_iter} slot of
+ the type structure for Python objects in the Python/C API.
+ \end{methoddesc}
+ 
+ The iterator objects themselves are required to support the following
+ two methods, which together form the \dfn{iterator protocol}:
+ 
+ \begin{methoddesc}[iterator]{__iter__}{}
+ Return the iterator object itself. This is required to allow both
+ containers and iterators to be used with the \keyword{for} and
+ \keyword{in} statements. This method corresponds to the
+ \member{tp_iter} slot of the type structure for Python objects in
+ the Python/C API.
+ \end{methoddesc}
+ 
+ \begin{methoddesc}[iteratpr]{next}{}
+ Return the next item from the container. If there are no further
+ items, raise the \exception{StopIteration} exception. This method
+ corresponds to the \member{tp_iternext} slot of the type structure
+ for Python objects in the Python/C API.
+ \end{methoddesc}
+ 
+ Python defines several iterator objects to support iteration over
+ general and specific sequence types, dictionaries, and other more
+ specialized forms. The specific types are not important beyond their
+ implementation of the iterator protocol.
+ 
+ 
 \subsection{Sequence Types \label{typesseq}}